Communications in a wireless communications network very frequently undergo interfering and masking which may appreciably lower the quality of the data received.
Traditionally, several methods are used to cope with these sources of imperfections. These methods are generally classified as solutions using spatial diversity and solutions using temporal diversity.
Spatial diversity, characterized by a repetition code, resolves the effects of masking in a wireless communication system by limiting data packet losses caused by physical obstacles which interrupt communications.
Temporal diversity for its part improves the robustness of the data by correcting a portion of the errors of the data packet related to poor conditions of transmission in the network.
These two types of approaches are complementary and can be implemented in one and the same communications network.
In a meshed wireless communications network, the application of the method known as the spatial diversity method makes the network robust by increasing the possibility that the destination nodes will receive an accurate copy. Indeed, the source node sends an original data packet which, depending on the repetition code chosen, is relayed or not relayed by another node of the network, commonly called a relay node. The criterion of selection of the relay node responsible for relaying the data packet is fundamental and determines the performance of the network.
However, the conditions of reception in a communications network may differ from one node to another. The repetition code used to make communications more robust against interference and masking, must take account of the conditions of the transmission channel proper to each pair formed by a source node and a receiver node within the communications network.
Indeed, through the use of an adaptive repetition code, each of the destinations can receive a large number of copies if the conditions of transmission to this destination greatly corrupt the data packets or else it can receive a small number of copies if the contrary is the case. The data copies received by the destination node are thus combined to achieve the smallest possible bit error rate (BER).